Fiber optic network architecture using high fiber-count fiber optic connectors

ABSTRACT

A fiber optic network architecture for distributing service to local subscribers is disclosed. The architecture includes a plurality of high-fiber count cables connected end-to-end at connectorized coupling locations to form a main cable trunk. The connectorized coupling locations include high-fiber count pass-through connections for optically connecting optical fibers of adjacent ones of the high-fiber count cables end. The connectorized coupling locations also including high-fiber count branch connections for optically connecting optical fibers of the high-fiber count cables to branch locations.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.15/563,010, filed on Sep. 29, 2017, which is a National StageApplication of PCT/US2016/025664, filed on Apr. 1, 2016, which claimsthe benefit of U.S. Patent Application Ser. No. 62/142,093, filed onApr. 2, 2015, the disclosures of which are incorporated herein byreference in their entireties. To the extent appropriate, a claim ofpriority is made to each of the above disclosed applications.

BACKGROUND

Fiber optic telecommunications technology has continued to expand asservice providers strive to deliver higher bandwidth communicationcapabilities to customers/subscribers. The phrase “fiber to the x”(FTTX) generically refers to any network architecture that uses opticalfiber in place of copper within a local distribution area. Example FTTXnetworks include fiber-to-the-node (FTTN) networks, fiber-to-the-curb(FTTC) networks and fiber-to-the-premises (FTTP) networks.

FTTN and FTTC networks use fiber optic cables that are run from aservice provider's central office to a cabinet serving a neighborhood.Subscribers connect to the cabinet using traditional copper cabletechnology such as coaxial cable or twisted pair wiring. The differencebetween an FTTN network and an FTTC network relates to the area servedby the cabinet. Typically, FTTC networks typically have cabinets closerto the subscribers that serve a smaller subscriber area than thecabinets of FTTN networks.

In an FTTP network, fiber optic cables are run from a service provider'scentral office all the way to the subscriber's premises. Example FTTPnetworks include fiber-to-the-home (FTTH) networks andfiber-to-the-building (FTTB) networks. In an FTTB network, optical fiberis routed from the central office over an optical distribution networkto an optical network terminal (ONT) located in a building. The ONTtypically includes active components that convert the optical signalsinto electrical signals in one direction and convert electrical signalsto optical signals in the opposite direction. The electrical signals aretypically routed from the ONT to the subscriber's residence or officespace using traditional copper cable technology. In an FTTH network,fiber optic cable is run from the service provider's central office toan ONT located at the subscriber's residence or office space. Onceagain, at the ONT, optical signals are typically converted intoelectrical signals for use with the subscriber's devices. However, tothe extent that an end user may have devices that are compatible withoptical signals, conversion of the optical signals to electrical signalsmay not be necessary.

A typical passive FTTP network includes fiber optic cables routed from acentral location (e.g., a service provider's central office) to a fiberdistribution hub (FDH) located in a local area such as a neighborhood.The fiber distribution hub typically includes a cabinet in which one ormore passive optical splitters are mounted. The splitters each arecapable of splitting a signal carried by a single fiber to a pluralityof fibers. A network of cables can be routed outwardly from the fiberdistribution hub to subscriber locations. For example, fiber opticcables can be routed from the fiber distribution hub to drop terminals(i.e., multi-service terminals), and drop cables can be routed from thedrop terminals to subscriber locations.

SUMMARY

Aspects of the present disclosure relate to fiber optic networkarchitectures that use high-fiber count fiber optic connectors tosimplify network installation operations thereby reducing networkinstallation times and reducing network installation costs.

Aspects of the present disclosure relate to fiber optic networkarchitectures that string together (e.g., daisy chain together) aplurality of high fiber-count fiber optic cables to form a main cableline. The high fiber-count fiber optic cables forming the main cableline are interconnected by connecting the high fiber-count fiber opticcables end-to-end at connection locations that include high fiber-countfiber optic connectors. In certain examples, high fiber-count fiberoptic connectors of a first high fiber-count fiber optic cable areconnected to high fiber-count fiber optic connectors of an adjacentsecond high fiber-count fiber optic cable at a first one of theconnection locations. In certain examples, high fiber-count connectorsof the first high fiber-count fiber optic cable are coupled to highfiber-count fiber optic connectors corresponding to fiber distributionhubs or other structures to allow signals to be branched off from themain cable line. In certain examples, the high fiber-count fiber opticconnectors each accommodate at least 72 optical fibers or at least 144optical fibers. In certain examples, a furcated fiber optic cable (e.g.,a bifurcated fiber optic cable) is used to couple a high fiber-countfiber optic connector of the first high fiber-count fiber optic cable toboth a high fiber-count fiber optic connector of the second highfiber-count fiber optic cable and to a high fiber-count fiber opticconnector corresponding to a fiber distribution hub. In certainexamples, the high fiber-count fiber optic connectors of the first andsecond high fiber-count fiber optic cables are configured such thateither end of the first high fiber-count fiber optic cable can beconnected to either end of the second high fiber-count fiber opticcable. Thus, during cable installation, it is not necessary to map orotherwise plan the orientation of each cable to ensure that adjacentends of adjacent cables in a series are compatible with each other.Instead, the cables are configured such that adjacent ends of the cableswill always be compatible with one another regardless of the cable endpositioning thereby facilitating the installation process and reducingthe likelihood of installation delays.

These and other features and advantages will be apparent from a readingof the following detailed description and a review of the associateddrawings. It is to be understood that both the forgoing generaldescription and the following detailed description are explanatory onlyand are not restrictive of the broad aspects of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a fiber optic architecture in accordancewith the principles of the present disclosure;

FIG. 2 schematically depicts a fiber distribution hub that can beincorporated into the architecture of FIG. 1;

FIG. 3 depicts a drop terminal that can be incorporated into thearchitecture of FIG. 1;

FIG. 4 is another view of the drop terminal of FIG. 3;

FIGS. 5 and 6 show 144-fiber optical connectors for supporting oppositeends of optical fiber ribbons routed through fiber optic cables of thearchitecture of FIG. 1;

FIGS. 7 and 8 provide routing charts specifying a routing scheme forrouting the optical fiber ribbons that extend between the 144-fiberconnectors of FIGS. 5 and 6, FIG. 7 corresponds to the connector of FIG.5 and FIG. 8 corresponds to the connector of FIG. 6;

FIGS. 9 and 10 show alternative 144-fiber optical connectors forsupporting the ends of optical fiber ribbons routed through cables inaccordance with the architecture of FIG. 1;

FIGS. 11 and 12 show further 144-fiber optical connectors suitable forsupporting the ends of ribbon fibers routed through the fiber opticcables of the architecture of FIG. 1;

FIGS. 13 and 14 show still further 144-fiber optical connectors suitablefor supporting the ends of optical fiber ribbons routed through fiberoptic cables in accordance with the architecture of FIG. 1;

FIGS. 15 and 16 show example 72-fiber optical connectors that can beutilized in the architecture of FIG. 1;

FIGS. 17 and 18 show still further fiber optic connectors that can beincorporated into the architecture of FIG. 1;

FIG. 19 shows an alternative architecture in accordance with theprinciples of the present disclosure that utilizes 72-fiber opticalconnectors;

FIGS. 20 and 21 show example 72-fiber optic connectors that can bemounted at opposite ends of optical fiber ribbons routed through fiberoptic cables utilized in the architecture of FIG. 19;

FIGS. 22 and 23 show additional 72-fiber optical connectors that can bemounted at opposite ends of fiber ribbons routed through fiber opticcables of the architecture of FIG. 19; and

FIG. 24 schematically depicts still a further fiber optic architecturein accordance with the principles of the present disclosure.

DETAILED DESCRIPTION A. Example Network Architecture

FIG. 1 illustrates an example architecture for an optical network 100 inaccordance with the principles of the present disclosure. As shown inFIG. 1, the network 100 is adapted to interconnect a central locationsuch as a central office 110 to a number of end subscribers 115 (alsocalled end users 115 herein). The central location may include opticalline terminals (OLT's) 116 that interface with the optical network 100.The central office may include patch panels or cross-connect panels forallowing selective connection and disconnection of individual lines withparticular equipment at the central office to provide customizedservice. The central office 110 may additionally connect to a largernetwork such as the Internet (not shown) and a public switched telephonenetwork (PSTN). The various cables of the network can be routed aeriallyor routed through underground conduit.

In general, the optical network 100 provides communication between thecentral office 100 of a service provider and the plurality ofsubscribers 115. The optical network 100 includes a series highfiber-count fiber optic cables 120 a-120 f routed from the centraloffice 110. The high fiber-count fiber optic cables 120 a-120 f can becoupled end-to-end in a daisy-chain fashion and can cooperate to definea main feeder cable trunk. The ends of the fiber high fiber-count fiberoptic cables 120 a-120 f can be coupled at connectorized cable couplinglocations 121. The connectorized cable coupling locations 121 caninclude high-fiber count connectorized pass-through connections 123having mating high-fiber count fiber optic connectors that areinterconnected to daisy chain the optical fibers of the high-fiber countfiber optic cables 120 a-120 f together to form the main cable trunk. Incertain examples the mating high-fiber count connectorized pass-throughconnections 123 can include sealed and robust multi-fiber connectorsthat are rated for outdoor use or otherwise compatible with outdoorenvironmental conditions. Such connectors can include robust fasteningelements such as threaded coupling nuts or sleeves or bayonet stylefastening elements for securing mated connectors together or to anintermediate fiber optic adapter. Seals can be provided for sealingbetween mated connectors or for sealing between the connectors and anintermediate fiber optic adapter. In other examples, the highfiber-count connectorized pass-through connections 123 can be moresuited for indoor conditions and can use indoor rated fiber opticconnectors. In the case where indoor fiber optic connectors are used,the connectorized cable coupling locations 121 can each include a sealedclosure or housing in which the indoor fiber optic connectors arehoused. In certain examples, high-fiber count fiber optic connectorsused at the high-fiber count connectorized pass-through connections 123can each support at least 24 optical fibers, at least 48 optical fibers,at least 72 optical fibers or at least 144 optical fibers.

The main feeder cable trunk can form an F1 portion/region of the opticalnetwork 100. The optical network 100 can also include local distributioncables 122 that extend out from the main feeder cable trunk. The localdistribution cables 122 can form an F2 portion/region of the opticalnetwork. Generally, the F2 portion of the optical network 100 is closerto the subscribers 115 than the F1 portion of the optical network 100.Local distribution cables are cables that are closer to the endusers/subscribers than the main trunk cable.

The network 100 also may include fiber distribution hubs (FDHs) 130 thatprovide interface locations between the main feeder cable trunk and thelocal distribution cables 122. In general, an FDH 130 is an equipmentenclosure that may include a plurality of passive optical splitters(e.g., 1-to-8 splitters, 1-to-16 splitters, or 1-to-32 splitters) forsplitting fiber optic signal lines from main the incoming feeder fibersinto a number of output distribution fibers corresponding to opticalfibers of the local distribution cables 122. The local distributioncables 122 are routed from the FDH 130 to locations in close proximityto the end users 115.

The connectorized cable coupling locations 121 are also adapted toprovide high-fiber count connectorized branch connections 125 betweenthe main cable trunk and the FDH's 130 or other type of terminal. Thehigh-fiber count connectorized branch connections 125 can includehigh-fiber count fiber optic connectors that each support at least 24optical fibers, at least 48 optical fibers, at least 72 optical fibersor at least 144 optical fibers. In certain examples the mating highfiber-count connectorized branch connections 125 can include sealed androbust connectors that are rated for outdoor use or otherwise compatiblewith outdoor environmental conditions. Such connectors can includerobust fastening elements such as threaded coupling nuts or sleeves orbayonet style fastening elements for securing mated connectors togetheror to an intermediate fiber optic adapter. Seals can be provided forsealing between mated connectors or for sealing between the connectorsand an intermediate fiber optic adapter. In other examples, thehigh-fiber count branch connections 125 can be more suited for indoorconditions.

The local distribution cables 122 can have a variety of different typesof configurations. As depicted at FIG. 1, the local distribution cables122 include a plurality of breakout locations 117 at which opticalfibers are separated out from and optically coupled to trunks of thelocal distribution cables 122. At a breakout location, fibers from thetrunk of the local distribution cable 122 can be broken out andconnectorized to form a branch such as a connectorized tether. In otherembodiments, fibers of the trunk of the local distribution cable can bebroken out and spliced to a length of optical fiber having aconnectorized free end so as to form a connectorized tether. The tetherscan be connected to drop terminals 104. In other examples, the localdistribution cables 122 may simply terminate at access terminals (e.g.,drop terminals 104) having one or more connection locations (e.g.,ports, fiber optic adapters, fiber optic connectors, splice locations,etc.) for connecting drop cables to subscriber locations (e.g., ONT's atthe subscriber locations) without having any intermediate/mid-spanbreak-outs.

As described above, in some embodiments, local distribution cables maynot employ mid-span breakouts. Instead, a local distribution cablecables may be run from an FDH to a drop terminal such that one end ofthe local distribution cable is located at the FDH and the other end ofthe F2 cable is located at the drop terminal. For such an embodiment,the local distribution cable may include the same number of opticalfibers as the number of access ports provided on the drop terminal. Forsuch an embodiment, an excess length of the F2 cable can be stored on aspool provided at the drop terminal as described at U.S. PatentApplication Ser. No. 61/098,494, which is hereby incorporated byreference. In other embodiments, an optical splitter may be provided inthe drop terminal so that the drop terminal can have more access portsthan the number of optical fibers fed to the drop terminal from thecorresponding local distribution cable.

B. Example Fiber Distribution Hub

FIG. 2 is a schematic diagram showing an example lay out that can beused for the FDHs 130 in the network of FIG. 1. Each FDH 130 generallyadministers connections at a termination region 211 between incomingfibers (e.g., fibers optically coupled to the high fiber-count cables120 a-120 f) and outgoing fibers (e.g., fibers optically coupled tosubscriber locations 115 typically corresponding to local distributioncables) in an Outside Plant (OSP) environment. The FDH 130 provides aninterconnect interface for optical transmission signals at a location inthe network where operational access and reconfiguration are desired.For example, the FDH 130 can be used to split (e.g., passively powersplit) the signals from the high fiber-count fiber optic cables 120a-120 f and direct the split signals to the local distribution cablesrouted toward the subscriber locations 115. In some cases, opticalsignals from the high fiber-count fiber optic cables 120 a-120 f maypass through the FDH 130 and be directed to a subscriber locationwithout being power split. In addition, the FDH 130 may be designed toaccommodate a range of alternative sizes and fiber counts and supportfactory installation of pigtails 208, fanouts, and splitter modules 250.Wavelength division multiplexers (e.g., coarse or dense wavelengthdivision multiplexers) can also be provided within the FDH 130 forseparating/dividing optical signals based on wavelength.

As shown at FIG. 1, the high fiber-count fiber optic cables 120 a-120 fcan be coupled to their respective FDH 130 by patch cords. The patchcords can have a furcated configuration (e.g., bifurcated as shown bypatch cords 127) or a single-ended configuration (e.g., see patch cord129). The connectorized ends of the patch cords can couple to the highfiber-count fiber optic connectors of the high-fiber count fiber opticcables 120 a-120 f and can also couple to high fiber-count fiber opticconnectors corresponding to the FDH's 130. The high fiber-count fiberoptic connectors can be mounted at external walls of housings of theFDH's 130 or mounted within fiber optic adapters mounted through theexternal walls so as to form connections locations (e.g., ports)accessible from outside the FDH housings. The high-fiber count fiberoptic connectors can also be positioned inside the housings of the FDH's130. In certain examples, the high fiber-count fiber optic connectorscan be mounted at the ends of stub cables 133 routed within the FDH's130. The stub cables can be positioned completely inside the FDH's orcan have connectorized ends that extend outside the FDH's. The stubcables 133 can include 12 fiber ribbons.

FIG. 2 shows an example one of the stub cables 133 having a free endterminated by one of the high fiber-count fiber optic connectors forproviding a connectorized branch connection 125 and an opposite endrouted to a connection interface 280 (e.g., fiber optic adapter modulesincluding fiber optic adapters for single fiber connectors, fiber opticadapters for interconnecting multi-fiber connectors such as 24 or12-fiber MPO connectors, a splice tray, etc.) within the FDH 130. At theinterface 280, one or more of the fibers of the stub cable 133 areoptically connected to splitter input fibers 206. The splitter inputfibers 206 can be routed from the interface 280 to a splitter mountinglocation 222 at which a plurality of the splitter modules 250 can bemounted. In certain embodiments, the interface 280 can be located at thesplitter mounting location 222 such that the splitter modules plugdirectly into the feeder cable interface (e.g., see U.S. Pat. No.7,418,181 that is hereby incorporated by reference). Each splittermodule 250 includes at least one fiber optic splitter 251 (e.g., apassive optical power splitter) positioned within a splitter housing253. At the splitter mounting location 222, the splitter input fibers206 are optically connected to separate splitter modules 250, whereinthe input fibers 206 are each split by the fiber optic splitters 251 ofthe splitter modules 250 into multiple pigtails 208, each having aconnectorized end 210.

At the interface 280, optical fibers of the stub cable 133 may also beoptically connected to pass-through fibers 207. Pass-through fibersallow signals from the main trunk cables to pass through the FDH to thelocal distribution cables without being optically power split. Thedepicted pass-through fiber 207 by-passes the optical splitters and isrouted to the termination region 211 for connection to a correspondingoptical fiber of one of the local distribution cables 122.

When splitter pigtails and pass-through pigtails are not in service,their connectorized ends can be temporarily stored on a storage module260 that is mounted at a storage region 213 of the FDH. When thepigtails are needed for service, the pigtails are routed from storageregion to a termination module 240 or other structure that is providedat the termination region 211. At the termination region 211, theconnectorized ends 210 of the pigtails can be connected to connectorizedends 214 of the fibers of the local distribution cables 122 by fiberoptic adapters 245. The termination region 211 can be the dividing linebetween the incoming fibers and the outgoing fibers. An example localdistribution cable 122 can forms the F2 portion of a network (seeFIG. 1) and typically includes a plurality of fibers (e.g., 72, 144,216, 432 fibers or other fiber counts) that are routed from the FDH 130toward subscriber locations 115. Example FDH's are disclosed at U.S.patent application Ser. Nos. 11/544,951 and 12/241,576 that are herebyincorporated by reference.

C. Example Drop Terminal

FIGS. 3 and 4 show an example configuration for the drop terminals 104used in the network of FIG. 1. The drop terminal configuration includesa housing 352. A plurality of fiber optic adapters 358 are mounted tothe housing 352. The adapters 358 include sealed, exterior ports 360that are accessible from the outside of the housing 352. In use,connectorized ends of drop cables 361 can be inserted into the exteriorports 360 to connect the drop cables to the network. The exterior ports360 are enclosed by plugs 362 when not connected to drop cables. Thefiber optic adapters 358 also include interior ports 364 that areaccessible from inside the housing 352. The interior ports 364 receiveinterior fiber optic connectors 366 (e.g., standard SC connectors asdisclosed at U.S. Pat. No. 5,317,663, which is hereby incorporated byreference) that are mounted to the ends of fibers 371 corresponding to afiber optic cable 367 (e.g., a local distribution cable) that is routedinto the interior of the housing 352. Further details about the dropterminal configuration can be found in U.S. application Ser. No.12/248,564, which is hereby incorporated by reference in its entirety.

D. Cabling and Connectorization

Referring to FIG. 1, the high fiber-count fiber optic cables 120 a-120 fare daisy-chained together to form a main cable trunk 119 that extendsin an upstream-to-downstream direction as the main trunk extends awayfrom a centralized location of a service provider (e.g., a centraloffice). In other words, a “downstream” direction is defined asextending generally away from the provider location and toward thesubscriber locations, and an “upstream” direction is defined asextending generally toward the provider location and generally away fromthe subscriber locations.

The connectorized coupling locations 121 of the optical network 100serve two basic purposes. First, the coupling locations 121 providehigh-fiber count connectorized pass-through connections 123 foroptically connecting together the ends of adjacent high fiber-countfiber optic cables 120 a-120 f so that the high fiber-count fiber opticcables 120 a-120 f can be strung together end-to-end. The connectionsare formed by mating high fiber-count connectors that may each support ahigh number of optical fibers such as 144, 72 or 24 optical fibers.Second, the coupling locations 121 allow for a certain number of opticalfibers to be branched (i.e., dropped out, separated, segregated, brokenout, etc.) from the main cable trunk and directed toward terminals suchas fiber distribution hubs 130. In certain examples, the couplinglocations 121 can provide high-fiber count connectorized branchconnections 125 for coupling certain optical fibers from the main cabletrunk to a corresponding fiber distribution hub positioned near thecoupling location 121.

It will be appreciated that the number of active fibers present in thehigh fiber-count fiber optic cables 120 a-120 f gradually/incrementallyreduces as the main cable trunk 119 extends in a downstream direction.This gradual/incremental reduction in the number of active fibers is theresult of fibers being branched from the main cable trunk 119 at each ofthe coupling locations 121. In the depicted configuration of FIG. 1, thecoupling locations 121 can include five coupling locations 121 a-121 f.

Referring to FIG. 1, the cable 120 b has fewer active fibers than thecable 120 a with the reduction in the number of active fibers beingequal to the number of fibers separated from the main cable trunk at thecoupling location 121 a and routed to fiber distribution hub 130 a. Thecable 120 c has fewer active fibers than the cable 120 b with thereduction in the number of active fibers being equal to the number offibers separated from the main cable trunk at the coupling location 121b and routed to fiber distribution hub 130 b. The cable 120 d has feweractive fibers than the cable 120 c with the reduction in the number ofactive fibers being equal to the number of fibers separated from themain cable trunk at the coupling location 121 c and routed to fiberdistribution hub 130 c. The cable 120 e has fewer active fibers than thecable 120 d with the reduction in the number of active fibers beingequal to the number of fibers separated from the main cable trunk at thecoupling location 121 d and routed to fiber distribution hub 130 d. Thecable 120 f has fewer active fibers than the cable 120 e with thereduction in the number of active fibers being equal to the number offibers separated from the main cable trunk at the coupling location 121e and routed to fiber distribution hub 130 e. The active fibers of thecable 120 f are optically coupled to the fiber distribution hub 130 f bya high-fiber count connectorized pass-through connection.

To promote manufacturing efficiency and inventory management, selectedones of the cables 120 a-120 e can have the same optical fiber countsand connectorization schemes. For example, certain adjacent cable pairscan have the same fiber counts with the downstream cable of the pairhaving a set of dark fibers equal in number to the number of fibersbroken out at the coupling location between the adjacent cables. In thedepicted example of FIG. 1, cables 120 a and 120 b have identical fibercounts and connectorization schemes, cables 120 c and 120 d haveidentical fiber counts and connectorization schemes, and cables 120 eand 120 f have identical fiber counts and connectorization schemes.

In one example, each of the cables 120 a, 120 b can include 432 fibersarranged in a ribbon stack having thirty-six 12-fiber ribbons with theends of the optical fibers being terminated by three of the highfiber-count fiber optic connectors for providing the pass-throughconnections 123 and/or branch connections 125. It will be appreciatedthat the high fiber-count connectors at the connections 123 or 125 caninclude mating 144 fiber optic connectors. While the fiber counts of thehigh fiber-count fiber optic cables 120 a, 120 b can be identical, thehigh fiber-count fiber optic cables 120 a, 120 b can have differentnumber of active fibers. For example, the high fiber-count fiber opticcable 120 a can include 432 active fibers, while the high fiber-countfiber optic cable 120 b can have a number of active fibers equal to 432fibers subtracted by the number of fibers broken out from the main fibertrunk to the fiber distribution hub 130 a at the coupling location 121a. In certain examples, 72 fibers can be broken out from the main fibertrunk at the coupling location 121 a and branched to the fiberdistribution hub 130 a. Thus, while the high fiber-count fiber opticcable 120 b includes 432 fibers, 72 of the fibers will be dark (i.e.,inactive). For example, fiber numbers 361-432 may be dark in the fiberoptic cable 120 b.

In one example, each of the cables 120 c, 120 d can include 288 fibersarranged in a ribbon stack having twenty-four 12-fiber ribbons with theends of the optical fibers being terminated by two high fiber-countfiber optic connectors. The connectors can be used to the form the highfiber count pass-through connections 123 and/or the branch connections125. The fiber count of each of the cables 120 c, 120 d equals thenumber of fibers present in the cable 120 a subtracted by the number offibers broken out at the upstream coupling locations 121 a, 121 b. Itwill be appreciated that the high fiber-count fiber optic connectorsforming the connections 123, 125 can each accommodate 144 fibers. Whilethe fiber counts of the high fiber-count fiber optic cables 120 c, 120 dcan be identical, the high fiber-count fiber optic cables 120 c, 120 dcan have different number of active fibers. For example, the highfiber-count fiber optic cable 120 c can include 288 active fibers, whilethe high fiber-count fiber optic cable 120 d can have a number of activefibers equal to 288 fibers subtracted by the number of fibers broken outfrom the main fiber trunk to the fiber distribution hub 130 c at thecoupling location 120 c. In certain examples, 72 fibers can be brokenout from the main fiber trunk at the coupling location 121 c andbranched to the fiber distribution hub 130 c. Thus, while the highfiber-count fiber optic cable 120 d includes 288 fibers, 72 of thefibers will be dark (i.e., inactive). For example, fiber numbers 216-288may be dark in the fiber optic cable 120 d.

In one example, each of the cables 120 e, 120 f can include 144 fibersarranged in a ribbon stack having twelve 12-fiber ribbons with the endsof the optical fibers being terminated by single high fiber-count fiberoptic connectors. The connectors can be used to the form the high fibercount pass-through connections 123 and/or the branch connections 125.The fiber count of each of the cables 120 e, 120 f equals the number offibers present in the cable 120 a subtracted by the number of fibersbroken out at the upstream coupling locations 121 a-121 d. It will beappreciated that the high fiber-count fiber optic connectors forming theconnections 123, 125 can each accommodate 144 fibers. While the fibercounts of the high fiber-count fiber optic cables 120 e, 120 f can beidentical, the high fiber-count fiber optic cables 120 e, 120 f can havedifferent number of active fibers. For example, the high fiber-countfiber optic cable 120 e can include 144 active fibers, while the highfiber-count fiber optic cable 120 f can have a number of active fibersequal to 144 fibers subtracted by the number of fibers broken out fromthe main fiber trunk to the fiber distribution hub 130 e at the couplinglocation 120 c. In certain examples, 72 fibers can be broken out fromthe main fiber trunk at the coupling location 121 e and branched to thefiber distribution hub 130 e. Thus, while the high fiber-count fiberoptic cable 120 f includes 144 fibers, 72 of the fibers will be dark(i.e., inactive). For example, fiber numbers 73-144 may be dark in thefiber optic cable 120 f The downstream end of the cable 120 f is coupledto the FDH 130 f.

Referring back to FIG. 1, one end of the fiber optic cable 120 a isconnected to the central office via high-fiber connectorizedpass-through connections 123, and the other end of the fiber optic cable120 a interfaces with the downstream fiber optic cable 120 b and the FDH130 a at the coupling location 121 a. The optical connections 123between the ends of the cables 120 a, 120 b are made by directconnector-to-connector couplings using the fiber optic connectorsmounted at corresponding ends of the fiber optic cables 120 a, 120 b. Afurcated patch cord 127 is used at the coupling location 121 a tooptically connect some fibers of the fiber optic cable 120 a to thefiber distribution hub 130 a and other fibers of the fiber optic cable120 a to the fiber optic cable 120 b. The furcated patch cord 127includes an upstream fiber optic connector 127 a and two downstreamfiber optic connectors 127 b. The upstream fiber optic connector 127 ahas a higher fiber count than each of the downstream fiber opticconnectors 127 b. The connector 127 a connects to the downstream end ofthe cable 120 a. The downstream fiber optic connectors 127 b connect tocorresponding fiber optic connectors provided at the fiber distributionhub 130 a and at the upstream end of the fiber optic cable 120 b. Thefurcated patch cord 127 includes a branch leg 137 that extends from theupstream fiber optic connector 127 a to the FDH 130 a and a pass-throughleg 139 that extends from the upstream fiber optic connector 127 a tothe upstream end of the fiber optic cable 120 b. In certain examples,the downstream connectors 127 b of the furcated patch cord 127 eachsupport half the number of optical fibers as compared to the upstreamconnector 127 a. In one example, the upstream fiber optic connector 127a of the furcated patch cord 127 a supports 144 fibers while each of thedownstream fiber optic connectors 127 b support 72 fibers.

At the coupling location 121 b, a downstream end of the fiber opticcable 120 b is optically coupled to an upstream end of the fiber opticcable 120 c. In certain examples, selected fibers of the fiber opticcable 120 b are optically connected to selected fibers of the fiberoptic cable 120 c by the high-fiber count connectorized pass-throughconnections 123 which may be formed by mating high-fiber count opticalconnectors (e.g., 144 fiber connectors). In certain examples, selectedfibers of the fiber optic cable 120 b are also coupled to the fiberdistribution hub 130 b by a patch cord 129 (e.g., a non-furcated patchcord). Opposite ends of the patch cord 129 are terminated by highfiber-count fiber optic connectors. An upstream end of the patch cord129 couples to selected fibers of the fiber optic cable 120 b and adownstream end of the patch cord 129 couples to the FDH 130 b.

The pass-through leg 139 of the furcated patch cord 127 may have fewerfibers than the mated downstream connector of the fiber optic cable 120b. Thus, a certain number of the optical fibers of the fiber optic cable120 b corresponding to the fiber optic connector mated to thepass-through leg 139 may be dark. In certain examples, half of thefibers of the fiber optic connector mated to the pass-through leg 139may be dark. It will be appreciated that the upstream end of the patchcord 129 can be connected to a fiber optic connector 123 a that isassociated with dark fibers. For example, half of the optical fiberscorresponding to the fiber optic connector 123 a may be dark fibers. Incertain examples, the patch cord 129 can have a reduced number ofoptical fibers that matches a number of active fibers corresponding tothe mating connector 123 a. In other examples the patch cord 129 canhave a number of optical fibers that matches a total number of fibers ofthe connector 123 a and certain fibers of the patch cord 129 maytherefore be dark.

The coupling location 121 c is located between the downstream end of thefiber optic cable 120 c and the upstream end of the fiber optic cable120 d. At the coupling location 120 c, a connection configurationsimilar to the one used at the coupling location 121 a can be used. Forexample, certain optical fibers of the fiber optic cable 120 c can bedirectly connected to corresponding optical fibers of the fiber opticcable 120 d by connectorized high-fiber count optical connections 123.All of the optical fibers corresponding to this connection are active.Additionally, a furcated patch cord 127 can be used to connect fibers ofthe fiber optic cable 120 c to the fiber distribution hub 130 c and toconnect other fibers to the fiber optic cable 120 d. The fiber opticconnector of the pass-through leg 139 of the furcated patch cord 127 hasfewer fibers than the mating connector located at the upstream end ofthe cable 120 d. Thus, certain optical fibers corresponding to the matedconnector are dark. In one example, half of the optical fibers (e.g.,72) of the fiber optic connector are dark. Branch leg 137 is routed tothe fiber distribution hub 130 c.

Coupling location 120 d is located between the downstream end of thefiber optic cable 120 d and the upstream end of the fiber optic cable120 e. The coupling location 121 d has a configuration similar to theone described with respect to the coupling location 121 b. Specifically,a non-furcated patch cord 129 is used to provide a branch connectionbetween the fiber optic cable 120 d and the FDH 130 d. Also, a directconnection via high-fiber count connectorized pass-through connections123 is also used to connect optical fibers of the fiber optic cable 120d to corresponding fibers of the fiber optic cable 120 e.

The coupling location 121 e is located between the downstream end of thefiber optic cable 120 e and the upstream end of the fiber optic cable120 f The coupling location 120 e uses a furcated patch cable 127 toconnect some of the fibers of the fiber optic cable 120 e to the fiberoptic cable 120 f and to connect the remainder of the fibers of thefiber optic cable 120 e to the FDH 130 e. The downstream end of thecable 120 f connects directly to the FDH 130 d. Because fibers have beenbranched out at the coupling location 120 e, it will be appreciated thatcertain fibers of the fiber optic cable 120 f are dark. For example,when 72 fibers are branched out at the coupling location 120 e, thenonly 72 fibers are active in the fiber optic cable 120 f and theremainder are dark.

It will be appreciated that the connectors at opposite ends (e.g., at“A” and “B” ends) of the cables 120 a-120 f can have identicalmechanical interfaces and can be intermateable with one another. In thisway, the cables 120 a-120 f can be installed in the field withoutconcern for which ends (i.e., “A” or “B”) are ultimately positionedadjacent to one another. In this way, regardless of how the cables arelaid out, the adjacent ends of the cables 120 a-120 f will be compatiblewith one another. In other words, “A” ends can be connected to “A” ends,“B” ends can be connected to “B” ends, and “A” ends can be connected to“B” ends.

FIGS. 5 and 6 show the end faces of two fiber optic connectors 223 a,223 b that can be positioned at opposite A and B ends of a given one ofone of the cables 120 a-120 f and that are optically connected to oneanother by optical fibers routed through the given one of the fiberoptic cables 120 a-120 f The connectors 223 a, 223 b can have identicalmechanical interfaces and can be inter-mated with one another. The fiberoptic connectors 223 a, 223 b include mechanical interfaces having oneor more alignment structures 220 for establishing a desired rotationalorientation when mated with a corresponding fiber optic adapter. Incertain examples, the alignment structures 220 can include keys such asprojections or recesses. The fiber optic connectors 223 a, 223 b alsoinclude connector bodies 221 supporting a plurality of ferrules 222 thatsupport end portions of optical fibers of the corresponding fiber opticcable. In one example, the ferrules 222 are twenty-four fiber ferruleseach supporting the end portions of twenty-four separate optical fibers.In certain examples, the end portions of the optical fibers are arrangedin two parallel rows 224 each including 12 separate optical fibers. Inthe embodiment of FIGS. 5 and 6, the connectors 223 a, 223 b eachinclude six ferrules 222 a-222 f arranged in a defined configurationrelative to the mechanical interface. In certain examples, the ferrules222 a-222 f are arranged consecutively in a row with each of theferrules 222 a-222 f arranged at a predefined location relative to themechanical interface.

In the embodiment of FIGS. 5 and 6, the ferrules 222 a-222 f can beseparated into two separate groups positioned on opposite sides ofreference planes 226 that generally bisect the end faces of the fiberoptic connector 223 a, 223 b. The groups of ferrules 222 can include afirst group 228 a positioned on one side of the reference plane 226 anda second group 228 b positioned on the opposite side of the referenceplane 226. The first group 228 a can include ferrules 222 a-222 c andthe second group 228 b can include ferrules 222 d-222 f. The ferrules ofthe second group 228 b can include vacant pin openings 230 while theferrules of the first group 228 a can include occupied pin openings 231.The occupied pin openings 231 support alignment pins 232 having baseends mounted within the occupied pin openings 231 such that thealignment pins 232 are fixed within the occupied pin openings 231. Inthe drawings, each alignment pin has been identified with an “X” whileeach vacant pin opening has been identified with an “0”.

It will be appreciated that the connectors 223 a or 223 b at adjacentends of the cables 120 a-120 f can be joined together by a suitablefiber optic adapter having opposite ports for receiving the connectorsdesired to be coupled together. The fiber optic adapter has keys or keyreceivers at each port are offset 180 degrees from one another about acentral axis of the adapter (e.g., the key or key receiver at one portis up and the key or key receiver at the other port is down). Thus,mated connectors 223 a or 223 b are flipped 180 degrees relative to oneanother about their central axes by the fiber optic adapter such thatfree ends of the alignment pins 232 of the connectors 223 a, 223 b matewith the vacant pin openings 230 of the connectors 223 a, 223 b when theconnectors 223 a, 223 b are coupled together.

The rows 224 of each ferrule 222 include an upper row 224 a and a lowerrow 224 b. The connectors 223 a, 223 b are each suited for supporting144 optical fibers. The optical fibers are preferably arranged inribbons within their corresponding cables 120 a-120 f with each ribbonincluding 12 fibers. Thus, within a given one of the fiber optic cables120 a-120 f, twelve ribbons are R1-R12 are routed through the cablebetween the corresponding fiber optic connectors 223 a, 223 brespectively at the opposite A and B ends of the cable. In certainexamples, the ribbons are routed using a polarity type A routingconfiguration. For example, ribbon R1 is routed from the top row 224 aof ferrule 222 a of the connector 223 a to bottom row 224 b of ferrule222 f of the connector 223 b. Ribbon R12 is routed from the bottom row224 b of ferrule 222 f of the connector 223 a to top row 224 a of theferrule 222 a of the connector 223 b. Thus, ribbons R1 and R2 are routedto symmetrically opposite ferrule positions with regard to the referenceplane 226 within the fiber optic connectors 123 at opposite ends of thecable. It will be appreciated that the remaining optical fiber ribbonsR2-R11 are similarly routed from ferrule positions on symmetricallyopposite sides of the reference plane 226. FIGS. 5 and 6 show a fiberlayout for each of the connectors 223 a, 223 b on opposite A and B endsof a given cable.

It will be appreciated that the fiber optic cables 120 a and 120 b caninclude 432 fibers arranged in thirty-six 12-fiber ribbons. The cables120 a, 120 b can includes three 144-fiber connectors 223 a, 223 bpositioned at opposite A and B ends of each of the cables 120 a, 120 b.FIG. 7 is a fiber layout 250 for end A of one of the fiber optic cables120 a, 120 b. FIG. 8 is a fiber layout 252 for end B of one of the fiberoptic cables 120 a, 120 b. As shown by FIGS. 7 and 8, ribbons 1-12 arerouted between a first pair of the connectors 223 a, 223 b positioned atopposite ends of the cable. Also, ribbons 13-24 are routed between asecond pair of the connectors 223 a, 223 b positioned at opposite endsof the cable. Further, ribbons 25-36 are routed between a third pair ofthe connectors 223 a, 223 b positioned at opposite ends of the cable.

FIGS. 9 and 10 show the end faces of two alternative fiber opticconnectors 323 a, 323 b that can be positioned at opposite A and B endsof a given one of one of the cables 120 a-120 f and that are opticallyconnected to one another by optical fibers routed through the given oneof the fiber optic cables 120 a-120 f The connector 323 a of FIG. 9 ismounted at an A end of a high fiber-count fiber optic cable and theconnector 323 b of FIG. 10 is mounted at a B end of the fiber opticcable. Optical fibers are routed through the fiber optic cable andsupported at each A and B end of the fiber optic cable by the connectors323 a, 323 b. It will be appreciated that the connectors 323 a and 323 bhave identical mechanical interfaces (e.g., keying structures) andidentical ferrule layouts. Additionally, the connectors 323 a, 323 b areintermateable with one another. In certain examples, mating of theconnectors 323 a, 323 b is facilitated through the use of a fiber opticadapter having opposite ports with keying structures that are positionedon the same sides of the ports (e.g., the keying structures can beprovided on the top sides of the ports, the bottom sides of the ports,the left sides of the ports, or the right sides of the ports). Thekeying structures of the adapter are configured to mate with the keyingstructures of the connectors 323 a, 323 b. In this way, when theconnectors 323 a, 323 b are mated together, the keying structures of theconnectors 323 a, 323 b are not flipped relative to one another.

Referring still to FIGS. 9 and 10, the connectors 323 a, 323 b includemechanical coupling interfaces including keying structures such as keys324. The connectors 323 a, 323 b also include six ferrules 322 a-322 farranged consecutively in a row. The ferrules 322 a-322 f are supportedby connector bodies 321. Each of the ferrules can support the endportions of 24 optical fibers. The end portions of the optical fiberscan be positioned in fiber openings defined by the ferrules. The fiberopenings can be arranged in two parallel rows for each ferrule. Theparallel rows can be positioned between two ferrule alignmentstructures. It will be appreciated that the alignment structures caninclude vacant pin openings 330 and occupied pin openings 331. Alignmentpins 332 are be fixed within the occupied pin openings 331. A “vacant”pin opening is a pin opening that is not filled with a pin when thegiven ferrule is not mated with another ferrule. When two ferrules aremated together, free ends of the pins 332 are received within the vacantpin openings 330.

In the example of FIGS. 9 and 10, the connectors 323 a, 323 b can bebisected by a reference plane 333 that also bisects each of the ferrules322 a-322 f as well as the keying structure. The vacant pin openings 330and the occupied pin openings 331 are arranged such that all of the pins332 are located on one side of the reference plane 333 while all of thevacant pin openings 330 are positioned on an opposite side of thereference plane 333. Each of the ferrules 322 a-322 f has one vacant pinopening 330 and one occupied pin opening 331.

Referring to FIGS. 9 and 10, twelve fiber ribbons R1-R12 are routedthrough the fiber optic cable between the connectors 323 a, 323 b. Theribbons can be routed using a layout strategy consistent with polaritytype B. In this type of arrangement, each of the ribbons R1-R12 isrouted to the same ferrule and the same fiber row for each of theconnectors 323 a, 323 b. However, the order of fibers at each row isreversed between the two connectors 323 a, 323 b. For example, fibersF1-F12 of the ribbon R1 respectively occupy positions 1-12 of the topfiber row of the ferrule 322 a and fibers F1-F12 of the ribbon R1respectively occupy positions 12-1 of the top fiber row of the ferrule322 a of the connector 323 b. Similarly, the ribbon R12 has fibersF133-F144 supported respectively at positions 1-12 of the bottom row offerrule 222 f of the connector 323 a and supported respectively atpositions 12-1 of the bottom row of the ferrule 222 f of the connector323 b. As shown at FIGS. 9 and 10, ribbons R2-R11 are routed in asimilar manner.

FIGS. 11 and 12 show the end faces of two alternative fiber opticconnectors 423 a, 423 b that can be positioned at opposite A and B endsof a given one of one of the cables 120 a-120 f and that are opticallyconnected to one another by optical fibers routed through the given oneof the fiber optic cables 120 a-120 f The connector 423 a of FIG. 11 ismounted at an A end of a high fiber-count fiber optic cable and theconnector 423 b of FIG. 12 is mounted at a B end of the fiber opticcable. In certain examples, the connectors 423 a, 423 b can havemechanical interfaces that are identical with one another and that areintermateable with one another. As depicted, the mechanical interfacescan include projections 425 and receptacles 427. When two of theconnectors 423 a, 423 b are mated, the projections 425 are receivedwithin the receptacles 427 to provide a mated connection and apredetermined rotational orientation between the connectors. Theconnectors 423 a, 423 b include six ferrules 422 a-422 f arrangedconsecutively in a row with each ferrule positioned at a specifiedlocation and orientation relative to the mechanical interface. Theferrules 422 a-422 f are supported by connector bodies 421. A referenceplane 426 divides the ferrules 422 a-422 f into a first group includingferrules 422 a-422 c and a second group including ferrules 422 d-422 fEach of the ferrules is depicted as a 24-fiber ferrule supporting tworows of optical fibers each including 12 optical fibers. The ferrules422 d-422 f have vacant pin openings 430 positioned on opposite sides ofthe fiber rows. The ferrules 422 a-422 c have occupied pin openings 431positioned on opposite sides of the rows of fibers. Pins 432 are fixedwithin the occupied pin openings 431.

It will be appreciated that twelve ribbons each having twelve fibers arerouted between the connectors 423 a, 423 b. The ribbons R1-R12 can berouted according to the same routing plan or scheme as described withrespect to the connectors 223 a, 223 b. The projections and receptacles425, 427 are configured such that when two connectors are mated, thegroups of ferrules 422 a-422 c and 422 d-422 f are flipped 180 degreesrelative to one another (i.e., rotated, transposed, inverted) therebyallowing the pins 432 and vacant pin openings 430 of the connectors tomate with one another and provide alignment between the optical fiberssupported by the mated ferrules. The connectors 423 a, 423 b can becoupled together without the use of an intermediate fiber optic adapter.Coupling sleeves, nuts, latches or other fasteners can be used to securethe connectors 423 a, 423 b together.

FIGS. 13 and 14 show the end faces of two further fiber optic connectors523 a, 523 b that can be positioned at opposite A and B ends of a givenone of one of the cables 120 a-120 f and that are optically connected toone another by optical fibers routed through the given one of the fiberoptic cables 120 a-120 f. The connector 523 a of FIG. 13 is mounted atan A end of a high fiber-count fiber optic cable and the connector 523 bof FIG. 14 is mounted at a B end of the fiber optic cable. In certainexamples, the connectors 523 a, 523 b can be 144 fiber connectors havingthe same ferrule configuration and fiber routing layout as theconnectors 223 a, 223 b. However, the connectors 523 a, 523 b havedifferent mechanical coupling interfaces from one another. For example,the connectors 523 a, 523 b can have keys 524 a, 524 b positioned atdifferent rotational positions on the connector body 521. The couplinginterfaces can be configured to prevent two of the same connectors frombeing coupled to one another (e.g., the “A” ends of two cables areprevented from being coupled together and the “B” ends of two cables areprevented from being coupled together). In certain examples, theconnectors 523 a, 523 b are coupled together by the use of anintermediate fiber optic adapter having a first port that only receivesa connector with a mechanical interface type depicted by the connector523 a and a second port configured to only receive a connector with amechanical interface of the type shown by the connector 523 b. With thistype of configuration, the installation process must be pre-planned suchthat adjacent ends of the cables are compatible and connectable to oneanother. In other words, the end of one cable must have a connector ofthe type depicted by the connector 523 a and the mating cable end musthave a connector of the type depicted by the connector 523 b. This typeof configuration is preferred for systems where it is desired to havethe ability to provide mid-span access locations along the length of agiven cable.

With regard to the connectors 523 a, 523 b of FIGS. 13 and 14, theconnectors can each have a row of consecutively positioned ferrules 522a-522 f of the type described previously with respect to the connectors223 a, 223 b. The ferrules can be supported on a connector body 521. Areference plane 533 can separate the ferrules into two groups. Theferrules 522 d-522 f on one side of a reference plane 533 can havevacant pin openings 530 while the ferrules 522 a-522 c on an oppositeside of the reference plane 533 can occupied pin openings 531 in whichalignment pins 532 are fixed. Fiber routing within a cable that extendsbetween the connectors 523 a, 523 b can have a layout of the typedescribed with respect to the connectors 223 a, 223 b. When theconnectors 523 a, 523 b are mated within a corresponding fiber opticadapter of the type described above, the rows of ferrules 522 a-522 fare flipped 180 degrees relative to one another to allow the pins 532 ofthe mated connectors 523 a, 523 b to mate with the vacant pin openings530 of the mated connectors 523 a, 523 b.

In the system of FIG. 1, mated 144 fiber connectors of the typedescribed above can be used to provide the connectorized pass-throughconnections 123. Additionally, 144 fiber connectors of the typedescribed above can be used at the ends of the non-furcated patch cords129. In this way, the patch cords 129 can couple to connectors at theends of the corresponding trunk cables and can also couple to likeconnectors provided at the FDH's or other branch locations. The upstreamconnectors 127 a of the furcated patch cords 127 can include 144 fiberconnectors of the type described above. The downstream connectors 127 bof the furcated patch cord 127 can include 72 fiber connectorsconfigured to be mateable with 144 fiber connectors of the typedescribed above. The FDH locations can include 72 or 144 fiberconnectors.

FIGS. 15 and 16 show end faces of 72-fiber optic connectors 623 a, 623 bthat are suitable for use as certain fiber optic connectors of thesystem of FIG. 1. The 72-fiber optical connectors 623 a, 623 b aremateable with each other and are also mateable/compatible with 144-fiberconnectors such as the connectors 223 a, 223 b. In certain examples, theconnectors 623 a, or 623 b can be used as the downstream connectors 127b of the furcated patch cords 127 and can also be provided at the FDHlocations. The fiber optic connectors 623 a, 623 b each include amechanical mating interface that includes an alignment key 624. Thefiber optic connectors 623 a, 623 b each include a row of consecutiveferrules 622 a-622 f supported on a connector body 621. The ferrules 622a-622 c are positioned on one side of a reference plane 633 while theferrules 622 d-622 f are positioned on an opposite side of the referenceplace 633. The ferrules 622 d-622 f have vacant pin openings 630 whilethe ferrules 622 a-622 c have alignment pins 632 fixed within occupiedpin openings 631. For the fiber optic connector 623 a, the ends ofseventy two fibers are supported by the ferrules 622 a-622 c. Each ofthe ferrules supports twenty-four fibers in two separate rows oftwenty-four fibers. The ferrules 622 d-622 f of the connector 623 a arevacant and do not support any optical fibers. The fiber optic connector623 b has an opposite fiber configuration as compared to the connector623 a. For example, with regard to the fiber optic connector 623 b, theferrules 622 d-622 f are twenty-four fiber ferrules that cooperate tosupport 72 optical fibers. The optical fibers are supported in two rowsof twelve fibers provided at each of the ferrules 622 d-622 f Theferrules 622 a-622 c of the connector 623 b are vacant and do notsupport any optical fibers.

It will be appreciated that either of the connectors 623 a, 623 b can bemated with the connectors 223 a, 223 b so as to provide a 72-fiberconnection between the intermated connectors. It will be appreciatedthat an intermediate fiber optic adapter can be used to mechanicallycouple and align the mated connectors.

With regard to the connectors 623 a, 623 b, it will be appreciated thattwo connectors having the configuration of 623 a cannot be matedtogether and two connectors having the configuration of 623 b cannot bemated together. Instead, it is intended for connectors having theconfiguration of 623 a to be mated with connectors having theconfiguration of connector 623 b. Fiber optic adapters can be used toalign and mechanically couple two of the fiber optic connectors 623 a,623 b.

FIGS. 17 and 18 show 72-fiber optical connectors 723 a, 723 b that aremateable with each other and are also mateable/compatible with 144-fiberconnectors such as the connectors 423 a, 423 b. In certain examples, theconnectors 723 a, or 723 b can be used as the downstream connectors 127b of the furcated patch cords 127 and can also be provided at the FDHlocations. Each of the connectors 723 a, 723 b includes mechanicalalignment structures (keying structures) such as projections 725 andreceptacles 727 that are configured to mate when two of the connectors723 a, 723 b are coupled together. The projections 725 and receptacles727 require the connectors 723 a, 723 b to be at a particular rotationalorientation relative to one another when coupled together. Similar tothe connectors previously described herein, the fiber optic connectors723 a, 723 b include a row of consecutively positioned ferrules 722a-722 f supported by a connector body 721. The ferrules 722 a-722 c arepositioned on one side of a bisecting reference plane 733 while theferrules 722 d-722 f are positioned on an opposite side of the bisectingreference plane 733. The ferrules 722 d-722 f are provided with occupiedpin openings 731 in which pins 732 are fixed and the ferrules 722 a-722c are provided with vacant pin openings 730. With regard to theconnectors 723 a, the ferrules 722 a-722 c are twenty-four fiberferrules that cooperate to support the ends of seventy-two opticalfibers. In contrast, the ferrules 722 d-722 f are blank and do notsupport any optical fibers. The connector 723 b has an opposite fiberarrangement as compared to the connector 723 a. For example, in theconnector 723 b, the ferrules 722 d-722 f are twenty-four fiber ferrulesthat cooperate to support the ends of seventy-two optical fibers, andthe ferrules 722 a-722 c are blank.

It will be appreciated that due to the arrangements of the fibers, twoof the connectors 723 a are not intended to be mated together, and twoof the connectors 723 b are not intended to be mated together. Instead,due to the flipped arrangement of the optical fibers, when mating two72-fiber connectors, it is desirable to couple a connector having theconfiguration of 723 a with a connector having the configuration of 723b. In this way, ferrules supporting fibers are mated with one anotherand ferrules that are blank are mated with one another.

FIG. 19 shows another optical network 800 in accordance with theprinciples of the present disclosure. Similar to the previouslydescribed network, optical network 800 can be used to distribute fiberoptic service from a centralized location to a plurality of subscriberlocations. The optical network 800 includes six fiber optic cables 820a-820 f that are optically connected in an end-to-end configuration. Thefiber optic cables 820 a-820 f are interconnected at coupling locations821 a-821 e. In the depicted example, the cable 820 a has 432 fibers,the cable 820 b has 432 fibers, the cable 820 c has 288 fibers, thecable 820 d has 288 fibers, the cable 820 e has 144 fibers, and thecable 820 f has 144 fibers. The various optical connections made in theoptical network 800 can be made with connectorized optical couplingsusing mated fiber optic connectors such as 72-fiber optical connectors.The 72-fiber optical connectors are used to optically connect the fiberoptic cables 820 a-820 f end-to-end via connectorized pass-throughconnections 823. The 72-fiber optical connectors are also used tooptically connect selected optical fibers of the fiber optic cables 820a-820 f to branch locations. The 72-fiber connectors can be provided atthe ends of connectorized patch cords 829 which provide connectorizedoptical couplings with the ends of the cables 820 a-820 f at thecoupling locations 821 a-821 f and with branch locations such as FDH's830 a-830 f. In the depicted embodiment of FIG. 19, 72 fibers arebranched out from the main trunk line at each of the coupling locations821 a-821 e.

In the optical network 800 of FIG. 19, a pattern is utilized where pairsof fiber optic cables having the same number of optical fibers areconnected together followed by subsequent pairs of fiber optic cableshaving reduced numbers of optical fibers. It will be appreciated thatthe first fiber optic cable in the pair typically has all live fiberswhile the second optical fiber in each pair has a plurality of darkfibers. The number of optical fibers in the optical pairs areincrementally stepped down as the main cable trunk extends in adownstream direction. In one example, the second pair of cables eachhave 144 fibers fewer than the first pair of fiber optic cables.Similarly, the third pair of fiber optic cables have 144 fibers fewerthan the second pair of fiber optic cables. In certain examples, 72fibers are branched out from the main trunk defined by the fiber opticcables 820 a-820 f at each of the coupling locations 821 a-821 f In thedepicted example, each cable that is the second in a pair of cables has72 dark fibers. It will be appreciated that the use of 72-fiber opticalconnectors greatly simplifies the network by reducing the number ofdifferent types of components that are used. It will be appreciated thatin certain examples, the 72-fiber connectors 623 a, 623 b or 723 a, 723b can be used to provide various connectorized optical connections ofthe optical network 800. In FIGS. 15-18, notations are provided thatlayout example fiber positioning within the connectors suitable forusing the connectors 623 a, 623 b or 723 a, 723 b at opposite A and Bends of an optical ribbon cable. Each connectorized coupling locationincludes mating fiber optic connectors.

FIGS. 20 and 21 show other 72-fiber connectors 923 a, 923 b suitable foruse in the optical network 800 of FIG. 19. The fiber optic connectors923 a, 923 b have the same configuration as the fiber optic connectors223 a, 223 b except ferrules 922 a-922 f support only 12 optical fibersas compared to 24 optical fibers. In a given optical cable containing aplurality of fiber ribbons, the fiber optic connectors 923 a, 923 b canbe mounted to the ribbons at opposite ends of the cable (e.g., at the“A” end and the “B” end). It will be appreciated that the fiber opticconnectors 923 a, 923 b have the same configuration and can be matedwith one another. Thus, the cables can connect “A” end to “A” end; “B”end to “B” end; or “A” end to “B” end without issue. It will beappreciated that the fiber ribbons within the cable can be routed in apolarity type A configuration between the ferrules 922 a-922 f of thefiber optic connectors 923 a, 923 b.

FIGS. 22 and 23 show further 72-fiber optical connectors 1023 a, 1023 bthat can be used in the optical network 800 of FIG. 19. The connectors1023 a, 1023 b have the same configuration as the connectors 423 a, 423b except ferrules 1022 a-1022 f each support only 12 fibers as comparedto 24 fibers. It will be appreciated that the connectors 1023 a, 1023 bhave identical configurations and are mateable with one another. In agiven optical cable containing a plurality of fiber ribbons, the fiberoptic connectors 1023 a, 1023 b can be mounted to the ribbons atopposite ends of the cable (e.g., at the “A” end and the “B” end). Theuse of the connectors 1023 a, 1023 b allows the cables to be connected“A” end to “A” end; “B” end to “B” end; or “A” end to “B” end. It willbe appreciated that the fiber ribbons within the cable can be routed ina polarity type A configuration between the ferrules 1022 a-1022 f ofthe fiber optic connectors 1023 a, 1023 b.

FIG. 24 shows a further optical network 1100 in accordance with theprinciples of the present disclosure. The network 1100 includes 6optical cables 1120 a-1120 f connected end to end. Similar to thepreviously described optical networks, the fiber optic cables can bearranged in pairs having the same number of optical fibers. As the trunkextends in a downstream direction, the number of fibers present in thecable pairs incrementally decreases. In certain examples, the number ofoptical fibers in subsequent cable pairs decreases by increments of 144fibers.

In the embodiment of FIG. 24, optical connections are made between thefiber optic cables 1120 a-1120 f by 24-fiber optical connectors 1123.Each 24-fiber connector can include a ferrule supporting two parallelrows of twelve optical fibers. The 24-fiber optical connectors provideconnectorized optical connections between adjacent fiber optic cables inthe trunk. The 24-fiber fiber optic connectors 1123 also provideconnections between optical fibers of the cables 1120 a-1120 f andbranch lines that extend to distribution components such as fiberdistribution hubs or other enclosures. In the depicted example, 72fibers are dropped at each of the interconnection locations between eachof the cable ends.

Similar to the previously described networks, optical network 1100 canbe used to distribute fiber optic service from a centralized location toa plurality of subscriber locations. The optical network 1100 includessix fiber optic cables 1120 a-1120 f that are optically connected in anend-to-end configuration. The fiber optic cables 1120 a-1120 f areinterconnected at coupling locations 1121 a-1121 e. In the depictedexample, the cable 1120 a has 432 fibers, the cable 1120 b has 432fibers, the cable 1120 c has 288 fibers, the cable 1120 d has 288fibers, the cable 1120 e has 144 fibers, and the cable 1120 f has 144fibers. The various optical connections made in the optical network 1100can be made with connectorized optical couplings using mated fiber opticconnectors such as 24-fiber optical connectors. The 24-fiber opticalconnectors are used to optically connect the fiber optic cables 1120a-1120 f end-to-end via connectorized pass-through connections. The atleast some 24-fiber optical connectors are also used optically connectselected optical fibers of the fiber optic cables 1120 a-1120 f tobranch locations. In certain examples, the branch connections can beprovided through the use of furcation cable assemblies 1127 (e.g.,fan-out cable assemblies, break-out cable assemblies). In certainexamples, the furcation cable assemblies can include a combined end 1127a having a single multi-fiber connector (e.g., a 72-fiber connector) andan opposite broken-out end having a plurality of legs 1127 b (e.g., 3legs) each connectorized with a multi-fiber connector (e.g., a 24-fiberconnector). All of the optical fibers of furcation cable assembly arepresent at the combined end 1127 a and the optical fibers can beseparated at a transition and divided between the legs 1127 b. In oneexample, the optical fibers are separated so as to be divided evenlybetween the legs 1127 b. In one example, the multi-fiber connector atthe combined end 1127 a supports more optical fibers then themulti-fiber connectors at the legs 1127 b. In one example, themulti-fiber connector at the combined end 1127 a supports a multiple ofthe number of fibers supported at the connector of each leg 1127 b. Inone example, the multiple is equal to the number of legs 1127 b (e.g., 3times in the depicted embodiment). The furcation cable assembly can beinstalled with the legs 1127 b upstream and the combined end 1127 adownstream. For example, the legs 1127 b can be coupled to endconnectors of the cables 1120 a-1120 f at the coupling locations 1121a-1121 f and the combined end 1127 a can be coupled to a matingconnector at an FDH.

From the forgoing detailed description, it will be evident thatmodifications and variations can be made without departing from thespirit and scope of the disclosure.

1-29. (canceled)
 30. A fiber optic connector, comprising: a connectorbody defining a mechanical interface and supporting a ferrulearrangement, the ferrule arrangement including: a plurality ofmulti-fiber ferrules arranged consecutively in a row of multi-fiberferrules, each of the multi-fiber ferrules including a plurality ofparallel rows of optical fiber openings for receiving optical fibers,the parallel rows of optical fiber openings being positioned between twoferrule alignment structures, the ferrule alignment structures includingan alignment pin at one side of the parallel rows of fiber openings anda vacant pin opening at an opposite side of the parallel rows of fiberopenings ferrules.
 31. The fiber optic connector of claim 30, whereinthe fiber optic connector is configured to optically couple to anotherfiber optic connector having an identically configured ferrulearrangement and an identically configured mechanical interface.
 32. Thefiber optic connector of claim 30, wherein the mechanical interfaceincludes a structure aligned with the row of the multi-fiber ferrules.33. The fiber optic connector of claim 32, wherein the structure is akey.
 34. The fiber optic connector of claim 33, wherein the key projectsfrom an outer surface of the connector body along a reference linedefined by the row of the multi-fiber ferrules.
 35. The fiber opticconnector of claim 34, wherein the key is configured to mate with afiber optic adapter to couple the connector body to the fiber opticadapter.
 36. The fiber optic connector of claim 30, wherein each of therows of the optical fiber openings includes twelve of the optical fiberopenings.
 37. The fiber optic connector of claim 30, including six ofthe multi-fiber ferrules arranged consecutively in the row ofmulti-fiber ferrules.
 38. The fiber optic connector of claim 30, whereinthe row of multi-fiber ferrules defines a first reference line; whereinthe alignment pins of the multi-fiber ferrules are aligned a long asecond reference line parallel to the first reference line; and whereinthe vacant pin openings are aligned a long a third reference lineparallel to the first and second reference lines.
 39. The fiber opticconnector of claim 30, wherein at least some of the optical fiberopenings are vacant.
 40. The fiber optic connector of claim 30, whereinthe alignment pins are fixed within occupied pin openings defined by theferrule bodies.
 41. A fiber optic connector, comprising: a connectorbody defining a mechanical interface and supporting a ferrulearrangement, the ferrule arrangement including: a plurality ofmulti-fiber ferrules arranged consecutively in a row of multi-fiberferrules, each of the multi-fiber ferrules including a plurality ofparallel rows of optical fiber openings for receiving optical fibers,the parallel rows of optical fiber openings being positioned between twoferrule alignment structures, the ferrule alignment structures includingan alignment pin at one side of the parallel rows of fiber openings anda vacant pin opening at an opposite side of the parallel rows of fiberopenings ferrules, wherein the mechanical interface includes a keystructure aligned with the row of the multi-fiber ferrules andprojecting from an outer surface of the connector body along a referenceline defined by the row of the multi-fiber ferrules.
 42. The fiber opticconnector of claim 41, wherein the key is configured to mate with afiber optic adapter to couple the connector body to the fiber opticadapter.
 43. The fiber optic connector of claim 41, wherein at leastsome of the optical fiber openings are vacant.
 44. The fiber opticconnector of claim 41, wherein the alignment pins are fixed withinoccupied pin openings defined by the ferrule bodies.